title: Blood pressure and mesenteric vascular reactivity in spontaneously hypertensive rats 7 months after gonadectomy.
abstract: OBJECTIVE
  Sexual dimorphism in the degree of high blood pressure (BP) has been observed in both animal and human hypertension. However, the mechanisms are still poorly understood. We tested the hypothesis that long-term loss of sex steroids promotes changes in mesenteric vascular reactivity that impact the maintenance of hypertension in the spontaneously hypertensive rats (SHR).
  
  
  METHODS
  Male SHR were sham operated (M-SHAM) or castrated (M-CX), and female SHR were sham-operated (F-SHAM) or ovariectomized (F-OVX) at 3 weeks of age. Seven months later, BP was measured in anesthetized rats, and vascular responsiveness was evaluated in the isolated perfused mesentery.
  
  
  RESULTS
  Mean arterial BP (mm Hg) was significantly greater in M-SHAM (186 ± 6) compared with F-SHAM (159 ± 5). Gonadectomy reduced BP in male SHR (M-CX: 160 ± 4) but had no significant effect in female SHR (F-OVX: 153 ± 7). Norepinephrine-induced constriction was similar in all groups. Gonadectomy attenuated serotonin-induced vasoconstriction in the mesentery. Acetylcholine (ACh)- and isoproterenol (ISO)-induced vasodilation was greater in female than male SHR. Ovariectomy of female SHR blunted ACh and ISO dilatory responses. ISO dose-response curves were shifted to the left in castrated male SHR.
  
  
  CONCLUSIONS
  Gonadectomy exerts long-term effects on mesenteric vascular reactivity and hypertension in the SHR.
authors.affiliation: UPMC McKeesport Family Medicine, McKeesport, PA, USA.
authors.forename: Rabelais
authors.initials: R
authors.lastname: Tatchum-Talom
authors.forename: Kathleen M
authors.initials: KM
authors.lastname: Eyster
authors.forename: Curtis K
authors.initials: CK
authors.lastname: Kost
authors.forename: Douglas S
authors.initials: DS
authors.lastname: Martin
mesh_terms: D000818:Animals; D001794:Blood Pressure / Q000187:drug effects* / Q000502:physiology; D005260:Female; D006066:Gonads / Q000601:surgery; D006973:Hypertension / Q000188:drug therapy* / Q000503:physiopathology*; D008297:Male; D008643:Mesentery / Q000187:drug effects* / Q000378:metabolism / Q000503:physiopathology*; D009638:Norepinephrine / Q000494:pharmacology; D009919:Orchiectomy; D010052:Ovariectomy; D051381:Rats; D011918:Rats, Inbred SHR; D012701:Serotonin / Q000494:pharmacology; D017366:Serotonin Receptor Agonists / Q000494:pharmacology; D013997:Time Factors; D014655:Vascular Resistance / Q000187:drug effects* / Q000502:physiology*; D014662:Vasoconstrictor Agents / Q000494:pharmacology
chemical_list: D017366:Serotonin Receptor Agonists; D014662:Vasoconstrictor Agents; D012701:Serotonin; D009638:Norepinephrine